Filtering device and method for neutralizing bad smells

ABSTRACT

The invention discloses a filtering device (1) for neutralizing volatile bad smells present in the atmosphere or carried by a flow of gas (5). The device comprises at least a layer (3) of natural zeolite material of set thickness impregnated with an aqueous solution with, for 100 parts by weight of zeolite, about 5 to about 20 parts by weight of the aqueous solution. This aqueous solution comprises for 1000 parts by weight of water, between about 1 part and about 20 parts by weight of a composite mixture comprising, for one part of ammonium ions or equivalent, one part of at least of one perfuming and/or deodorising composition.

The present invention relates to a filtration device for neutralizingthe volatile unpleasant odors present in an atmosphere or conveyed by astream of gas.

The invention also relates to a process using such a filtration.

The invention finds a particularly important, although not exclusive,application in the field of treating unpleasant odors such as body odorsin bathrooms or in hairstyling salons, kitchen odors and tobacco odors,as well as particularly tenacious odors such as those of excrement orthe odors of decomposing materials in public refuse sites.

The invention is also applicable to odors from factory chimneys, frompurification plants and more generally to any malodorous gaseouseffluent arising from industrial, commercial or residential sites.

Various methods and devices for treating unpleasant odors are alreadyknown.

A first technique consists in overcoming these odors by masking, eitherquantitatively by perfuming the atmosphere with a large amount of a morepleasant aromatic product, or by binding the malodorous molecules, ingeneral by complexing them with other molecules, to give a product whichhas a different and more pleasant aroma.

However, this masking technique has drawbacks, since such asuperposition does not completely eliminate the unpleasant odors, inparticular given the very great sensitivity of human olfactory nerves.

For example, man remains sensitive to hydrogen sulfide even when itsproportion in the atmosphere does not exceed 3 ppm.

Another technique envisaged is that of filtration.

This consists in reducing the unpleasant odors by filtering theodoriferous molecules during emission.

Thus, filters containing active charcoals which give acceptable resultsare known. However, since such filters cannot be absolute in practice,they allow malodorous molecules to pass through.

The present invention is directed toward providing a device and aprocess for treating unpleasant odors, which device and process arebetter than those previously known in terms of meeting the practicalrequirements, in particular as regards allowing better air purificationin a simple, effective and inexpensive manner.

By using, in combination, mechanical filtration, with adsorption of themalodorous molecules, and release of perfuming molecules and/or of acomposition of these pleasant-smelling molecules, the atmosphere or thestream of malodorous gas treated are thus purified and pleasantlyperfumed.

With this aim, the invention proposes essentially a filtration devicefor neutralizing the volatile unpleasant odors present in an atmosphereor conveyed by a stream of gas, characterized in that it includes atleast one layer of material made of natural zeolite of determinedthickness, said layer being impregnated with an aqueous solution, with,per 100 parts by weight of zeolite, about 5 to about 20 parts by weightof said aqueous solution, said aqueous solution comprising, per 1000parts by weight of water, between about 1 part and about 20 parts byweight of a composite mixture comprising, per one part of ammonium ionsor equivalent, one part of at least one composition of perfuming and/ordeodorizing nature.

The thickness of the layer is determined in a manner within thecapability of those skilled in the art, as a function of the specificuse of the filter depending on the characteristics of the filtered, gas,i.e. essentially the average flow rate of the malodorous moleculespassing through the filter.

The adsorbing nature of the natural zeolite, the humidification of theatmosphere achieved by means of this filter appropriately impregnatedwith water and renewed over time, as well as the possibilities ofrelease of perfuming and/or deodorizing molecules into the stream offiltered gas or into the filtered atmosphere, thus allow excellentphysicochemical purification.

In advantageous embodiments, use is furthermore made of one and/or otherof the following provisions:

the aqueous solution is cationic;

the aqueous solution comprises between about 3 parts and about 10 partsof composite mixture;

the layer made of natural zeolite is formed of granular material, withan average particle size of between about 0.1 cm and about 5 cm;

the composition of perfuming and/or deodorizing nature comprises anamount, which is effective for neutralizing the unpleasant odors, of asolvent represented by the following structural formula: ##STR1## inwhich n is an integer from 2 to 4, A, B and C each independentlyrepresent hydrogen, a lower alkyl group containing 1 to 5 carbon atomsor a lower alkenyl group containing 3 to 5 carbon atoms, on conditionthat when two of the groups, A, B and C, are alkyl or alkenyl groups,they are attached to different carbon atoms and provided that the sum ofthe carbon atoms in A, B and C is not greater than 7, R1 and R2 eachindependently represent hydrogen or a lower alkyl group containing 1 to5 carbon atoms, in which R1 and R2 together represent CH2m in which m isan integer from 2 to 6, R3 represents hydrogen or a lower alkyl oralkenyl group containing up to 6 carbon atoms, provided that the sum ofthe greatest number of carbon atoms in R1 or R2 plus R3 is not greaterthan 10.

Such compounds used in solvent form have molecules which are partlyhydrophilic and partly hydrophobic, which have shown, unexpectedly,during tests carried out, that they improve the mechanism ofimpregnation of the zeolite and of release of the perfuming and/ordeodorizing composition;

the composition of perfuming and/or deodorizing nature is produced fromaromatic esters and/or from a complex aldehyde formation;

the composition of perfuming nature comprises a first aldehyde chosenfrom acyclic and non-terpenic aliphatic aldehydes, alicyclicnon-terpenic aldehydes, terpenic aldehydes, aliphatic aldehydessubstituted with an aromatic group and biofunctional aldehydes and/or asecond aldehyde chosen from aldehydes containing unsaturation α to thealdehyde function conjugated with an aromatic ring and aldehydes whosefunction is borne by an aromatic ring;

the natural zeolite comprises at least one type of zeolite chosen fromclinoptilotite, mordenite, chabazite, erionite, phillipsite, heulanditeand analcime, and/or originating from any lithium-bearing deposit ofmaterial of zeolite type comprising physicochemical characteristicsshowing qualities equivalent to those of the materials mentioned above,of adsorption, of catalysis and of exchange,

the device comprises means for forced circulation of the stream of gasthrough the layer of material in the device.

The invention also proposes a process for treating the volatileunpleasant odors present in an atmosphere or conveyed by a stream ofgas, characterized in that the atmosphere or the stream of gas istreated by filtration with a filter composed of a layer of material madeof natural zeolite of determined thickness impregnated with an aqueoussolution, with, per 100 parts by weight of zeolite, about 5 to about 20parts by weight of said aqueous solution, said aqueous solutioncomprising, per 1000 parts by weight of water, between about 1 part andabout 20 parts by weight of a composite mixture comprising, per one partof ammonium ions or equivalent, one part of at least one composition ofperfuming and/or deodorizing nature.

Advantageously, forced circulation of the atmosphere or of the stream ofgas through the filter is carried out by sucking the atmosphere or thestream of gas through the filter.

The invention will be understood more clearly on reading the descriptionwhich follows of specific embodiments, given by way of non-limitingexample.

FIG. 1 schematically shows an embodiment of the device according to theinvention arranged above a stream of gas to be deodorized.

FIG. 2 is a schematic view of a layer of zeolite material according tothe invention. The structure is, for example, metallic, painted, of moreor less cylindrical external shape.

FIG. 1 schematically shows a removable filtering device or filter 1,comprising a structure 2 for supporting two horizontal circular layers3, for example identical layers, made of granular material based onzeolite according to the invention.

The layers are of determined thickness, for example each is 5 cm inthickness.

The filter 1 is placed above a well 4 for evacuation of decompositiongases 5 charged with unpleasant odors arising from storing rotting waste6, which is incidentally covered with a layer of earth 7.

The external dimension of the filter and the outside diameter of thecircular layers depends on the width of the well 4.

The supporting structure 2 rests on the edge of the well via a conicalsupport 8 allowing the approximately leaktight conveyance of the gases,which rise here by natural extraction, and their passage through thefilter.

This filter comprises a central chimney 9 which is cylindrical in thetop part, closed off, for example, at mid-height of the filter, with aconical seat at the bottom part allowing the gases to be guided.

The chimney 9 is open-worked or railed in on the side walls 10 of itscylindrical top part so as to allow the passage of the gases radiallytoward the outside and through the walls of said chimney, in order topenetrate into the lower layer 3 of the filter, which it then crossesvertically, as well as the upper layer 3.

Each layer (see FIG. 2) rests on a sieve in the shape of a metal washer11, for gravitational support of the granular material 12, compacted andhumidified with a composite mixture according to the invention.

The layers of zeolite are humidified, for example, via a dropwisegravitational flow, from a tank 13 for storing the composite mixture 14,whose level 15 is checked regularly, for example via a visual indicator16.

More specifically, the tank 13 feeds, for example, two manifolds 17 withevenly spaced suction nozzles, each of said manifolds being located atthe periphery or in the center, above the upper circular surface of acorresponding layer.

In order to allow installation of the manifold for the lower layer, theupper surface 18 of this layer emerges into a circular space 19, whichis closed on its walls, separating the two layers.

The upper surface 20 of the upper layer emerges into the open air inorder to release the purified and/or perfumed gases 21.

A roof 22 for protecting against bad weather, for example in the form ofa Chinese hat represented as a mixed line in FIG. 1, is moreoverprovided.

Lastly, the base of the structure 2 is formed by a circular tank 23 forholding the composite mixture which has not been absorbed by thezeolite. It is bounded on one side by the lower conical seat of thechimney 9 and on the other side by the outer wall of the structure.

If overfilled, the composite mixture impregnates the lower face of thelower layer 3, and runs off via the overspill in the chimney 9 towardthe well 4.

The filter 1 can be fully dismantled, for example from the top, therebyallowing the layers 3 of zeolite to be replaced.

To do this, handles 25 for holding the layers 3 are provided, each beinginserted into a cohesion envelope 26 with reinforced corners 27.

The envelope 26 is designed to rest on stops 28 fixed to the inner wallsof the structure 2.

This results in great simplicity, robustness and particularly noteworthyreliability with regard to carrying out filter maintenance.

In general, as regards the composite mixture, as compounds which may besuitable according to the invention, mention will be made of thecompounds chosen from the following:

aliphatic alcohols, advantageously C10 to C12 alcohols, such as decanol,citronellol and geraniol;

aldehydes, advantageously C10 to C13 aldehydes, which are eitheraliphatic, such as normal or branched dodecanal and myrac aldehyde, orare aromatic, such as cyclamen aldehyde, helional, heliotropin,para-methylphenylacetaldehyde and vanillin and its derivatives;

aliphatic ketones, advantageously C13 and C14 ketones, such as α- andβ-ionones and damascones, as well as aliphatic and aromatic ketones witha musk odor which can contain up to 18 carbon atoms;

aliphatic esters, advantageously C8 and C15 esters, such as methyldihydrojasmonate, methyl jasmonate, methyl cinnamate and ethylmethylphenylglycidate, and aromatic esters such as methyl anthranilate,methyl N-methylanthranilate, p-cresyl phenylacetate and amyl salicylate;

aromatic lactones such as coumarin and dihydrocoumarin and aliphaticlactones such as δ-decalactone, dodecalactone and undecalactone;

phenols such as eugenol and isoeugenol;

aromatic ethers such as diphenyl oxide naphthol methyl and ethyl ethers,and galaxolide;

nitrogenous compounds, for instance amines such as indole and itscompounds of reaction with hydroxycitronellal, referred to as indoline,and aliphatic nitriles such as tridecene-2-nitrile;

aromatic amines, including pyridine derivatives, such as2-(2'-methyl-2'-pentenyl)-5-methylpyridine.

Among the compounds mentioned above which are suitable according to theinvention, mention will preferably be made of coumarin, allylionone,eugenol, isoeugenol, methyl dihydrojasmonate, indole, indolene,helional, α-ionone, β-ionone and2-(2'-methyl-2'-pentenyl)-5-methylpyridine.

Those compounds which are liquid can be used just as they are. On theother hand, the crystalline compounds will be used after they have beendissolved in their usual solvent well known in perfumery, such as ethylphthalate, benzyl benzoate, ethyl citrate and the like.

In addition, if so desired, the compounds according to the invention canalso be used as a mixture in variable proportions giving a formulationwhich has virtually no unpleasant olfactory effect.

However, there is nothing to prevent one from adding to the compoundsaccording to the invention, taken alone or as mixtures, and as desired,other perfuming starting materials which enhance the olfactory effect ofthe formulation to be applied for the user and for the environment.

In order to better illustrate the advantageous results obtained with theprocess according to the invention, two examples are given below,without any limitation whatsoever implied.

The test used is carried out with a panel of at least 50 people, atleast five of whom are olfaction specialists, the others being selectedwithout any particular criterion.

The effluent to be treated is defined in the following way:

For a quantifiable and isolated effluent, for example H2S:

by physical reduction:

By measuring its concentration in air before treatment and itsconcentration in the filtered air,

by sensitive reduction:

To do this, the sensations perceived by inhaling, by means of anolfactometer or a beaker test:

the air treated with the filtration system and impregnated withdeodorizing solution,

two "decoy" samples, one perfumed and the other malodorous,

air artificially charged with an H2S concentration identical to that ofthe treated air, without deodorizing solution, are graded on a scale ofintensity by the entire panel.

In the case of a malodorous effluent of complex type, for example onearising from an organic degradation, the sensations perceived byinhaling, by means of an olfactometer or a beaker test:

the air treated with the filtration system and impregnated withdeodorizing solution,

two "decoy" samples, one perfumed and the other malodorous of anothernature,

a sample of unperfumed air charged with H² S, at the residualconcentration recorded for treated air, are graded on a scale ofintensity by the entire panel.

In all the cases, the panel members grade their sensations on twograduated scales (A and B) by distinguishing the intensity of theunpleasant odor (scale --A--) and the total intensity of the odor (scale--B--).

Given the temporary anosmia which is induced by this technique, it isrecommended to wait at least one minute between two samples. Thiswaiting period can be filled, either by a question of control or bysmelling or tasting an entirely different product (eau de toilette,chewing-gum).

The original odor receives a value of 0 on the graduated scales.

For each scale, the graduation ranges, in steps of 5, from -20 to +20,the grade -20 representing absolute neutrality and the absence of anyolfactory sensation.

The results are obtained by taking the average, for each scale, of thegrades assigned by the panel members.

Scale A:

An average below 0 reflects a reduction in the unpleasant odor, anaverage above 0 reflects an increase in the unpleasant odor.

Scale B:

An average below 0 reflects a reduction in the intensity of the odorperceived, an average above 0 reflects an increase in the intensity ofthe odor perceived.

The results are then analyzed according to the following criteria:

An average A above 0, with an average above 0 reveals a masking effect,

an average A below 0, with an average above 0 reveals aninhibition-reduction effect.

Given the residual traces of malodorous effluents and of perfumingmolecules, it is considered that the optimum result is in the range-5/-10 for Scales A and B.

Test 1:

Air charged with 40 ppm of H2S at 20° C.

Zeolite filter granules of 0.8/1.2 cm

Clinoptinolite

Thickness: 40 mm

Soaked with 15% by weight of an aqueous composite solution based onammonium ions, esters, aldehydes and solvents, of the type known underthe name Vailex sold by the company Bush Boake Allen, at a concentrationof 5 per 1000.

Air flow rate: 0.04 m/second

Results observed:

a) Measurement of the H2S concentration after filtration: 7 ppm

b) residual odor--control sample: air +7 ppm H2S, corresponding to the 0value of scales A and B

panel result for the residual odor: Scale A: -6 and Scale B: -5

Test No. 2:

Strong odor of organic decomposition (sample taken from a refuse site)

Presence of Bio-gas, methane, mercaptans, H2S, NH3, etc.

Zeolite filter granules of 0.8/1.2 cm

50% clinoptilite--50% chabazite

Thickness: 30 mm

Soaked with 15% by weight of an aqueous composite solution based onammonium ions, esters, aldehydes and solvents, of the type known underthe name Vailex, at a concentration of 4 per 1000.

Air flow rate: 0.1 m/second

Panel result for the residual odor: Scale A: -8 and Scale B: -6.

As goes without saying and as can be seen from the above, the presentinvention is not limited to the embodiment described more particularly.Rather, it embraces all the variants and in particular those in whichthe filter comprises means for generating forced circulation, those inwhich it comprises only one layer or several layers of zeolite-basedmaterial and those in which the humidification system is different.

What is claimed is:
 1. Process for treating the volatile unpleasantodors present in an atmosphere or conveyed by a stream of gas, in whichprocess the atmosphere or the stream of gas is treated by filtrationwith a filter composed of a layer of adsorbent material of determinedthickness impregnated with an aqueous solution, with, per 100 parts byweight of material, about 5 to about 20 parts by weight of said aqueoussolution, characterized in that the material is natural zeolitecomprising at least one material chosen from clinoptilotite, mordenite,chabazite, erionite, phillipsite, heulandite and analcime,said aqueoussolution comprising, per 1000 parts by weight of water, between about 1part and about 20 parts by weight of a composite mixture comprising, perone part of ammonium ions or equivalent, one part of at least onecomposition of perfuming and/or deodorizing nature.
 2. Process accordingto claim 1, characterized in that forced circulation of the atmosphereor of the stream of gas through the filter is carried out by suckingsaid atmosphere or said stream of gas through said filter.
 3. Filtrationdevice (1) for neutralizing the volatile unpleasant odors present in anatmosphere or conveyed by a stream of gas (5), this device comprising atleast one layer (3) of adsorbent material (12) of determined thicknessimpregnated with an aqueous solution (14), with, per 100 parts by weightof material, about 5 parts to about 20 parts by weight of said aqueoussolution, characterized in thatthe material is natural zeolitecomprising at least one material chosen from clinoptilolite, mordenite,chabazite, erionite, phillipsite, heulandite and analcime, in that thedevice comprises humidification means and in that said aqueous solutionis cationic and comprises, per 1000 parts by weight of water, betweenabout 1 part and about 20 parts by weight of a composite mixturecomprising, per one part of ammonium ions or equivalent, one part of atleast one composition of perfuming and/or deodorizing nature.
 4. Deviceaccording to claim 3, characterized in that the aqueous solutioncomprises between about 3 parts and about 10 parts of composite mixture.5. Device according to claim 3, characterized in that the layer (3) madeof natural zeolite is formed of granular material with an averageparticle size of between about 0.1 cm and about 5 cm.
 6. Deviceaccording to claim 3, characterized in that the composition of perfumingand/or deodorizing nature comprises an amount, which is effective forneutralizing the unpleasant odors, of a compound represented by thefollowing structural formula: ##STR2## in which n is an integer from 2to 4, A, B and C each independently represent hydrogen, a lower alkylgroup containing 1 to 5 carbon atoms or a lower alkenyl group containing3 to 5 carbon atoms, on condition that when two of the groups, A, B andC, are alkyl or alkenyl groups, they are attached to different carbonatoms and provided that the sum of the carbon atoms in A, B and C is notgreater than 7, R1 and R2 each independently represent hydrogen or alower alkyl group containing 1 to 5 carbon atoms, in which R1 and R2together represent CH2m in which m is an integer from 2 to 6, R3represents hydrogen or a lower alkyl or alkenyl group containing up to 6carbon atoms, provided that the sum of the greatest number of carbonatoms in R1 or R2 plus R3 is not greater than
 10. 7. Device according toclaim 3, characterized in that the composition of perfuming and/ordeodorizing nature is produced from aromatic esters and/or from acomplex aldehyde formation.
 8. Device according to claim 7,characterized in that the perfuming composition comprises a firstaldehyde chosen from acyclic and non-terpenic aliphatic aldehydes,alicyclic non-terpenic aldehydes, terpenic aldehydes, aliphaticaldehydes substituted with an aromatic group and biofunctional aldehydesand a second aldehyde chosen from aldehydes containing unsaturation α tothe aldehyde function conjugated with an aromatic ring and aldehydeswhose function is borne by an aromatic ring.
 9. Device according toclaim 3, characterized in that it also comprises means for forcedcirculation of the stream of gas through the layer of material in thedevice.